Method of driving rotation of a rotorcraft rotor by anticipating torque needs between two rotary speed setpoints of the rotor

A method of driving rotation of at least one rotorcraft rotor by a power plant of the rotorcraft, the method comprising the following operations:

• a control unit identifying a required speed (Nr) for driving rotation of at least one vertical-axis main rotor of the rotorcraft, the required speed (Nr) being calculated by applying a first calculation rule incorporating at least a first calculation parameter giving rise to controlled variation, within a predefined range of values, in the value of the required speed (Nr) depending on variation in the value of the first calculation parameter;
• the control unit applying a method of calculating a power setpoint to be delivered by the power plant, the calculation of the power setpoint being based at least on applying a second calculation rule incorporating at least one second calculation parameter for calculating anticipated power (Pf) that the power plant must deliver as a function at least of loads supported by the main rotor driven at the previously-identified required speed (Nr);
• and
• transmitting at least one control order (C) relating at least to the power setpoint to a power plant regulator, the regulator causing the power plant to be operated to drive the at least one rotor in rotation in compliance with driving the main rotor in rotation at the required speed (Nr), the regulator comprising at least one regulator unit for regulating injection of fuel to at least one fuel-burning engine of the power plant;
• wherein the second calculation rule for calculating the power setpoint (Pt) incorporates at least one third calculation parameter concerning a power surplus (S), the power surplus (S) relating to progressive power needs to be delivered from a current power (Pc) for driving the main rotor at a current speed (V) of rotation to an anticipated power (Pf) for driving the main rotor at the required speed (Nr).

A rotorcraft comprising:

• a vertical-axis main rotor;
• a power plant for driving rotation of the rotor;
• a control unit for identifying a required speed (Nr) for driving rotation of the vertical-axis main rotor, the required speed (Nr) being calculatable by applying a first calculation rule incorporating at least a first calculation parameter giving rise to controlled variation, within a predefined range of values, in the value of the required speed (Nr) depending on variation in the value of the first calculation parameter;
• the control unit capable of applying a method of calculating a power setpoint to be delivered by the power plant, the calculation of the power setpoint being based at least on applying a second calculation rule incorporating at least one second calculation parameter for calculating anticipated power (Pf) that the power plant must deliver as a function at least of loads supported by the main rotor driven at the previously-identified required speed (Nr), and transmitting at least one control order (C) relating at least to the power setpoint to regulator means for regulating the operation of the power plant, the regulator means capable of causing the power plant to be operated to drive the rotor in rotation in compliance with driving the main rotor in rotation at the required speed (Nr), the regulator means comprising at least one regulator unit for regulating injection of fuel to at least one fuel-burning engine of the power plant;
• wherein the second calculation rule for calculating the power setpoint (Pt) incorporates at least one third calculation parameter concerning a power surplus (S), the power surplus (S) relating to progressive power needs to be delivered from a current power (Pc) for driving the main rotor at a current speed (V) of rotation to an anticipated power (Pf) for driving the main rotor at the required speed (Nr).